The pie turned out pretty tasty!
Here's how I made it: I boiled the broccoli for about 5 minutes, drained, then ran cool water over it to stop it from cooking. I cooked two ginormous potatoes and made mashed potatoes with them.
Then I poached 300g of salmon in 425ml of semi-skimmed milk, along with 10 peppercorns, a chunk of onion, a clove of garlic, and two bay leaves. I poached it for about 10 minutes or until the salmon was cooked through. I pulled that out of the milk, then poured the milk mixture through a sieve and reserved the liquid. I made a roux with about a tablespoon of Flora (trying to be healthy!) and tablespoon of flour. I poured the milk mixture back into the roux to make a cream sauce. I dumped in a load of dried parsley, added some salt and fresh ground black pepper. I let that cook until it thickened up a bit. Layered the pieces of salmon and broccoli in a square baking dish, poured the sauce on top, then spread the mash potato over top. I baked it in a preheated oven (190C) for about 35 minutes.
It turned out nice, but there are some things I would do different next time. I would definitely bake it in a dish that is a bit more narrow and deep. The sauce boiled up into the mash and it was a little hard to differentiate the two layers. I was also going to pour a little white wine into the poaching liquid, but we didn't have any (drank it all last weekend!). I will do this next time. I didn't add cheese because I wanted to keep it low fat, but grated cheese on top would have been tasty as well.